Endoscopes and imaging catheters are widely used in many medical procedures for viewing areas of bodily organs, cavities, passageways, etc. Generally, such imaging devices include an elongate sheath or similar structure wherein optical fibers are arranged both for transmitting illumination light to the distal end of the sheath to illuminate a viewing field, and for carrying an optical image back to a viewing port or camera. One or more lenses may be positioned on the distal end of the imaging device to focus the optical image received by, or the illumination cast by the instrument.
In many applications, it is desirable that the distal portion of the imaging device be “steerable”, bendable or maneuverable from the proximal end of the device to facilitate guidance of the device through tortuous or furcated anatomical passageways. Additionally, the ability to bend the device at or near its distal end may enable the operator to visually scan an expanded viewing area by bending or otherwise manipulating the distal end of the device Second, the ability to maneuver the tip makes it easier to guide the tip of the device properly through the often highly branched and convoluted passageways near organs such as the coronary arteries of the heart or the branched ducts of the biliary tree.
In order to effect and control the deflection of the distal tip of an imaging device, many designs have been introduced that incorporate either two opposed control wires to control bending in one plane or four wires evenly spaced to control bending in two perpendicular planes. These control wires run the length of the device and terminate at the distal end of the steerable region or at the distal tip. The proximal end of each control wire is functionally connected to a separate drum or spool rotated by a dedicated electrical or fluid motor for linearly advancing and retracting the control wire in relation to the device. In operation, when one of the control wires is pulled proximally by rotation of the drum or spool, the distal tip of the device bends at the steerable region toward the retracted wire.